Devices have been proposed to convert an electrical signal, representative of image information, to a corresponding imagewise pattern of light. Such conversion devices, hereinafter "image sources", can provide a light image or portion thereof for image display, imagewise exposure of a photosensitive medium, or for delivery to an image information transmission or sensing system.
For example, in a typical image recording system, an image source may be used to provide a pattern of light that exposes and thus alters a photosensitive recording medium, in an imagewise fashion. The desired image may be composed and made visible on the recording medium, such as photographic film, or upon other types of receiving media from which the image is transferred to a hard copy medium, such as those used in the electrophotographic art.
If used as an image display device, an image source is expected to produce a light pattern that is directly viewable by a human observer. The pattern may be composed by accumulating line-by-line portions of the image to be displayed, or an entire image frame may be produced substantially at once. For example, planar image display devices have found application as alpha-numeric displays.